Mechanism of action of the benzodiazepines
Benzodiazepines (BDZs) bind to the gamma sub-unit of the GABA-A receptor. Their binding causes an allosteric (structural) modification of the receptor that results in an increase in GABA A receptor activity. BDZs do not substitute for GABA, which bind at the alpha sub-unit, but increase the frequency of channel opening events which leads to an increase in chloride ion conductance and inhibition of the action potential
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References
Sedative-hypnotic drugs. In: Basic and clinical pharmacology, 8th edition. Katzung BG. USA: The McGraw Hill Companies, Inc, 2001:364–381.